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4hv.org :: Forums :: Electromagnetic Radiation
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Amateurs testing the EM-drive?

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Robert Clark
Sun Aug 13 2017, 12:32AM Print
Robert Clark Registered Member #58454 Joined: Thu Feb 18 2016, 06:33AM
Location:
Posts: 23
This article gives a skeptical review of the experiments testing the EM-drive:

SCIENCE — NASA’s EM-drive still a WTF-thruster. New paper generates more noise than experimental thrust. CHRIS LEE - 11/22/2016, 5:17 PM
Link2

The researchers measured 128 micronewtons at 60 watts in vacuum. The problem is this thrust is very small so its difficult to rule out experimental errors. It's about the weight of a grain of sand.

They would be better off to redo the experiment at much higher powers. This actually isn't that hard to do. For instance common household microwave ovens put out 1,000 watts. So using six of these to get 6,000 watts you should get, if it is a real effect, in the range of 12.8 milliNewtons, or 12.8/9.81 = 1.3 milliKilograms-force = 1.3 grams-force. Forces at this weight range, about the weight of a cubic centimeter of water, are commonly measured in university labs.

In fact, this could probably tested by amateurs or university students. You can find amateur experimenters who have posted on the net various (dangerous!) experiments with microwave generators, magnetrons, taken from out-of-use microwave ovens:

Crazy Ukrainians Experiment with Microwaves.
Lindsay Handmer at 10:01 AM Jul 30 2014
Link2,390449

The hardest part would be doing the EM-drive experiment in a vacuum though. Experiments showing positive results that have been done in air can be discounted because air currents can be the cause of the results observed.

For instance, here's an amateur doing a test of the EM-drive in air showing positive results. Numerous commenters to the video observed the results are unreliable because of the effect of heated air generating rising air currents:

EmDrive Test No.03 Success, I have thrust !!! - YouTube.


For an amateur though doing the experiment at high power in a vacuum chamber would be expensive because of the large size of the required vacuum chamber able to hold six 1,000 watt magnetrons. What might work is to use a waveguide to direct all the microwave energy to a small area that can be enclosed in a small vacuum chamber.

Bob Clark
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Sulaiman
Sun Aug 13 2017, 07:21AM
Sulaiman Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I doubt that approach will help,
. getting 6 magnetrons to reliably phase-lock would require a lot of experimentation
. if the microvaves enter via a waveguide, this may add its own forces when carrying microwave power
(electromagnetic waves have momentum)
. 6 times more signal power from 6 times the weight and volume does not help much.

I have avoided playing with domestic magnetrons because the hv, and especially the rf, scare me,
and I've never had a use that outweighed these two concerns.
I used to work on a LINAC, using 4x 20 MW klystrons so I understand the physics a little,
here is a fairly recent document that I came across which may help a little


]weioa04.pdf[/file]
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Robert Clark
Sun Aug 13 2017, 12:30PM
Robert Clark Registered Member #58454 Joined: Thu Feb 18 2016, 06:33AM
Location:
Posts: 23
Sulaiman wrote ...

I doubt that approach will help,
. getting 6 magnetrons to reliably phase-lock would require a lot of experimentation
. if the microvaves enter via a waveguide, this may add its own forces when carrying microwave power
(electromagnetic waves have momentum)
. 6 times more signal power from 6 times the weight and volume does not help much.

I have avoided playing with domestic magnetrons because the hv, and especially the rf, scare me,
and I've never had a use that outweighed these two concerns.
I used to work on a LINAC, using 4x 20 MW klystrons so I understand the physics a little,
here is a fairly recent document that I came across which may help a little





Wow! Was that 100 MW total power continuous???

Some of these amateurs do experiments with multiple microwave generators combining their power:

TRIO OF MAGNETRONS POWER A MICROWAVE RIFLE. Dan Maloney October 22, 2016
Link2

Obviously if such is to be done in a university undergraduate lab it would have to be done under microwave expert supervision.

About the waveguide addings its own forces, the proposers of the EM-drive have considered that, and argue the results they've seen are orders of magnitude higher than that due to electromagnetic wave's momentum.


Bob Clark
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Dr. Slack
Sun Aug 13 2017, 05:01PM
Dr. Slack Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
From what I read of the recent NASA vacuum experiments, a lot of the odd behaviour seemed to be due to the heating of the apparatus when under power, so unwanted/assymetrical torsion beam expansion rather than aircurrents. Without better experimental design, increasing the operating power would just increase the uncertainties. The interdigitated electrostatic calibration motor was quite capable of generating nice crisp torque steps, so there was no issue with sensitivity even down at that low power level. At its very least, the technique has to show torque/thrust monotonic with input power, and IIRC even that wasn't achieved.
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Hazmatt_(The Underdog)
Sun Aug 13 2017, 05:28PM
Hazmatt_(The Underdog) Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
Where is Bill Nye?

Isn't he supposed to "back this up" as "viable" technology, and call for the extermination of the "deniers"?

HAHAHHAH.
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DerAlbi
Mon Aug 14 2017, 05:44AM
DerAlbi Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Robert, dont make a fool out of your self, this magnetron combining is fake as fuck. There is neither a appropriate power delivery system on their stick nor do they wear any eye protection.. which is the one body part thats most susceptible to RF heating.
Even if this thing does actually output RF energy, think again if those 4 batteries could ever deliver the power to even drive one magnetron to its full potential. The whole thing is a piece of shit (technically). I guess its fine if you call it art-work.
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Hazmatt_(The Underdog)
Tue Aug 15 2017, 01:50AM
Hazmatt_(The Underdog) Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
Yea a real setup would require those magnetrons be connected to some rectangular transition (it'd be huge, like 2" x 4" transition) then it would have to be coupled to a "Magic Tee" to sum the power.
All of which have to be silver plated, and even then it would get very hot.
The magnetrons would probably arc over constantly because they are not really being loaded, or would probably burn out faster because of reflected power.
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Sulaiman
Tue Aug 15 2017, 09:27AM
Sulaiman Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I disagree;

They are generating short intense microwave pulses, so do not need huge batteries, and body-part damage due to heating is minimal.
(I'm of the opinion that there is more to rf damage to humans than just thermal effects, but I'm in the minority)

The horn antenna would load the magnetrons, it is a fairly efficient transmit antenna.

Magnetrons can be 'tuned' to phase lock, as they mentioned in the video.

The rf interference on the video gives a good clue to operation.

Would you walk back home through town wearing those outfits if you did not have to ?

I think that at least some of the video is real, and realistic.



I'm unable to do the math for the e.m. drive and I don't really understand it so I can't comment other than, whether it works or not, it will not make any difference to me in my little shed/workshop/lab/hideaway :)





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dexter
Tue Aug 15 2017, 10:29AM
dexter Registered Member #42796 Joined: Mon Jan 13 2014, 06:34PM
Location:
Posts: 195
i don't get how the EM drive could ever generates trust... wouldn't the microwaves also bounce from the cone walls thus negating the top and bottom plates bounce inequality?
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DerAlbi
Tue Aug 15 2017, 11:42AM
DerAlbi Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Sulamain.. which EM interference? You mean the video editing to simulate image sensor artifacts? All that why they press the trigger and simulate the thing would have some kind of recoil to make it more like shooting something?
One question: why would an image sensor be affected (and that only partially at a time, so you can still see the action for youtube!!), but the MP4 or whatever encoding processor works flawlessly... do you have ever seen a blocky corrupted encoded file? Guess what, it wouldnt look good on youtube.
Also have you ever seen an overloaded image sensor due to laser damage? Those image artefacts take a lot of time to vanish... also the purple nature of the artifacts is very interesting. Somehow the 2.45GHz of the magnetrons manage to excite only the blue and red sensors, but not the green ones which there are twice as much of....
Please, think critically; dont say its true because you wish it was..
And its not a short pulse. The duration of the simulated image sensor artefacts (if they were true) can last a second or more... 3 Magnetrons would have a power of at least 2kW... this means 2000J energy delivery.... you are on the forum long enough to know how a 2kJ energy storage looks like... i just wonder why you ignore the basics. unbelievable that one has to debunk a video like this on a forum like that. shouldnt happen. cry
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